Thanks, mate, for making things clear for me. If you put it like this, I’m definitely culpable 

cryotosensei

Punishment is not your job. You can only make rational consequences.

If all students are bad, there is probably a reason. Ask them.

AskSN

When was the last time you got reproached?

It is, if you are not a sport teacher.
You also can not punish all students.
Punishment is not your job. You can only make rational consequences. 
If all students are bad, there is probably a reason. Ask them.